Currently, surgery commonly applied for injecting or filling medical fillers into bones is performed in the following ways:
A mechanical-type hole expansion device, such as is disclosed in U.S. Patent Application Publication Nos. 20110196494, 2011018447, 20100076426, 20070067034, 20060009689, 20050143827, and 20220052623, and U.S. Pat. Nos. 6,354,995, and 6,676,665, is utilized to expand a hole in the bone and create a space, where the hole expansion device is removed after the hole has been bored; a covering device is then inserted before the process of pouring or stuffing medical fillers takes place. This type of surgery has the following shortcoming: The cancellous bone fragments that are crushed by the mechanical-type hole expansion device often fall into the mechanical-type hole expansion device, causing the device to jam and its components unable to be retracted, i.e., unable to be restored to a state of contraction, which in turn causes the entire mechanical-type hole expansion device to become stuck at the location of the hole and unable to be removed.
A filling-type hole expansion device, such as is disclosed in U.S. Pat. Nos. 5,972,015, 6,066,152, 6,235,043, 6,423,083, 6,607,544, 6,623,505, 6,663,646, and 6,716,216, also bores a hole in the bone to create a space, where the hole expansion device is removed after the hole is bored, and a covering device is placed therein, and then the surgery with the pouring or stuffing of the medical filler takes place. Mostly, the filling-type hole expansion device has a balloon (the type of balloon used depends on what is needed) disposed inside the bone with liquid, such as water, poured into the balloon with high pressure, causing the balloon to expand and push away the cancellous bone, achieving the effect of hole expansion. The filling-type hole expansion device also has shortcomings. For example, the balloons used in the process must be attached to a nozzle, which creates the possibility that the balloon may be detached from the nozzle during the high-pressure insertion of liquid into said balloon. There can even be cases where the balloon ruptures.
In the case that a hole expansion process is not done beforehand, and a covering device is placed directly into the bone for the insertion of medical fillers, the hole expansion is instead achieved through the pressure created when medical fillers are inserted into the covering device. In this case the covering device acts as both a hole expansion device and a fixation device as disclosed in, for example, Taiwan patent No. 1321467, Taiwan Patent application publication No. 20112995, and U.S. Pat. No. 6,248,110. It is also possible to exclude a covering device entirely, instead using a perfusion device to directly pour medical filler at the surgery location, such as what U.S. Pat. No. 5,514,137 discloses to reinforce fixation at the surgery location. The surgical way has the following shortcomings: due to the lack of a hole bored before surgery, the area for pouring the medical filler cannot be controlled accurately to cause the direction of the poured medical filler differing from what doctors originally predicted. It can even be the case that, after the medical filler has been poured in, the bone is found to be not completely held up by the covering device, or the medical filler spreads out all over in the bone, or even seeps out of the bone; it might occur that the concentration of slurry-type medical filler is too dilute, or the grains of the medical filler are too fine such that it results in the bone not being successfully held up during the pouring of medical filler, to greatly decrease the originally-expected effectiveness.
A mechanical-type hole expansion device, which is utilized as the bone fixation device such as is disclosed in U.S. patent Application Publication Nos. 20120071977, 20110046739, 20100069913, 20100217335, 20090234395, and 20090005821 is implanted into and props up the bone, with the medical filler being poured immediately afterward to surround the mechanical-type hole expansion device. After pouring, the hole expansion device is left inside the body along with the medical filler. Due to the lack of a covering device, it is not possible to effectively control the flow direction of the medical filler, and the medical filler can therefore spread out in all directions or even flow out of the bone. Besides, the medical filler cannot effectively and fully cover the mechanical-type hole expansion device, and it may follow that the mechanical-type hole expansion device gradually contracts to a state of partly expanding instead of the state of completely expanding. That in turn causes the bone to not be fully propped up, thereby failing to accomplish the original purpose of bone fixation.
The present invention is a bone fixation device which uses a covering part to cover its expansion part. During the hole expansion process, the covering part can effectively prevent any falling of cancellous bone into the expansion part, which allows the expansion part to expand and contract smoothly and repeatedly in the bone to adjust the direction and extent of the hole expansion. In addition, when the medical filler is poured in, the area which poured by the medical filler can be controlled effectively to avoid the medical filler spreading all over in the bone. After pouring is completed, the medical filler can completely cover the expansion part to avoid the expansion part contracting.